Hey guys, I was watching an old Doctor Who (The War Games, 2nd Doctor), and I came across a phrase scrawled on the wall: "Roll on death demobs too far away"

I assumed it was a set direction left behind by accident, ha ha, but when I googled it, it is apparently a phrase used by a small amount of people. However, there was no definition. From context, it seems to be something of a brave stand against death, but I really have no idea. Anyone?